This is a sashimi variation of a finned x-wing. Either the fin in r4c6 is true, or the x-wing in r16c68 is true (note that a finned x-wing, like most other swordfish, does not require a candidate at every vertex, hence the sashimi variation). In either case you can eliminate the 6's in r6c45. On other sites, this pattern has also been called a sky-scraper, as well as, apparently, a fork.

Note that like other fish, there is a complementary finned fish (in this case a finned jellyfish) in the rows, as shown below...

Thanks for making clear the logic underlying the fork, which indeed it is.

I was wrong to call it a finned X-wing. It is more like two finned X-wings in one pattern. This is what Myth Jellies means by “a sashimi variation of a finned x-wing,” though perhaps it awards a rather grandiose title to such a humble, if useful, tool.

Another name for this is "simple coloring" because there is a strong link (only two <6> candidates) in R1. Just follow the chain a b c d, and you conclude a or d must be <6>.

The "fork", which is a form of multi-coloring, does not require this strong link. Suppose there are other candidates <6> in R1. Then, we can still say: at least one of a and d is <6>.

If a is <6>, the assertion is true.
If a is not <6>, b is <6>, c is not <6>, and <d> is <6>.

(Actually, without the strong link in R1, it is possible that both a and d are <6>.)

This belongs in your bag of tools because you can easily look for the pattern while looking for X-wings. The fork is two strong links that line up at one end. The X-wing is two strong links that line up at both ends.

There are only two places for X in the second row, cells r2c2 and r2c6. There are only two places for X in the second column, box 1 and cell r6c1. As box 1 contains a single X, one or other of r2c6 and r6c1 must contain it. Accordingly X may be eliminated from r6c6.

That it is all a fork is: two places for a candidate,

By all mean think of this as a trivial example of colouring, a turbot, an empty rectangle or a nice loop, if you find it more straightforward. However, the fork is an elementary concept at about the level of the X-wing. It can itself be useful on occasion.

It forms a building block in these more widely applicable techniques but using "fork" as a drscription of them adds several layers of confusion to an already confusing litany of terms.